|Maintainer||Edward Kmett <email@example.com>|
NB: this contradicts another common meaning for an
Category, which is one
where the pentagonal condition does not hold, but for which there is an identity.
A category with an associative bifunctor satisfying Mac Lane's pentagonal coherence identity law:
bimap id associate . associate . bimap associate id = associate . associate bimap disassociate id . disassociate . bimap id disassociate = disassociate . disassociate